Methods and Results: This multicenter prospective single-arm trial with historical controls will include patients who are aged ≥20 years and will undergo cardiac catheterization for suspected acute myocardial infarction (AMI). Patients will receive an intravenous bolus administration of concentrated sodium bicarbonate solution (7% or 8.4%, 20 mEq) and will be observed for 72±12 h. Data for the control group, comprising all patients who underwent PCI for AMI between January 1, 2020 and December 31, 2020 across participating hospitals, will be extracted. The primary endpoint is the incidence of CIN, defined as an increase in serum creatinine of >0.5 mg/dL or >25% from baseline within 48±12 h. We will evaluate the endpoints in the prospective group and compare them with those in the historical control group.